Not to big of a deal. I had 1/3 of my membrane make a giant bubble 10 years or so ago. Most of the bubble will push back down onto the glue and will stay in place if you seal the front edge and keep the air out. Screwing some lathe into the seam and side to side every 6 inches or so will keep it down until you get home.
IF the membrane is still intact you can re-glue with a better contact cement once you get home and then use EPDM tape on the front edge and any screw holes you made to get it home. You may need to slit and fold back the membrane to get the contact cement all the way to the edge of the bubble when making the permanent repair.
One hint for a permanent front edge hold down and seal, mix up some All Purpose Bondo and go over the front edge where the transition between the metal and membrane is then cover that with the EPDM tape.